1. Field of the Invention
The technical scope of the invention is that of devices enabling the control of an active steering system.
2. Description of the Related Art
Active steering systems are organs to steer a vehicle that enable a turn command given by the driver to be corrected when this command risks compromising the vehicle's stability.
Thus, a device is known by patent FR-2681449 in which a computer evaluates a potential oversteering set point based on a measurement of the angular yaw speed and determines a counter-steering set point that is applied to the steering organ to correct the steering lock.
This correction is more often than not made by a mechanical differential. Indeed, such equipment enables a set point command (for example, given by a steering wheel) to be combined with a correction command given by a motor that is piloted by the computer as a function of the roll measurements that are made.
U.S. Pat. No. 7,063,636 discloses such an active steering device in which the steering wheel acts on the input of a differential whereas an electric motor to correct the steering lock acts on the planet carrier of the differential.
With such a device, piloting is still possible even in the event of the failure of the correction motor. There is, in fact, a direct link via the differential between the steering wheel and the output controlling the wheels.
However, such a device is associated with hydraulic power steering that to a certain extent compensates for the shocks or force feedback that might be communicated to the steering wheel when the compensation motor is started up.
Such an active steering device is not always implemented, namely in vehicles employing skid driving or skid steering vehicle, such as tracked vehicles or non-drive wheel vehicles.
In fact, in these vehicles the steering control is amplified using specific means formed of the hydrostatic steering unit. These means are positioned downstream of the steering differential and are not able to dampen the shocks caused by the steering correction motor.